GigaOm reports that Skyhook Wireless will offer a coordinates plug-in for AOL Instant Messenger later this year: The plug-in will allow people to announce their location using Skyhook's constantly refreshed database of Wi-Fi access points that allows GPS-like precision in urban areas, less so the more rural you go. AIM users with the plug-in will be able to see when buddies are physically nearby and plot their buddies' locations on a map. I assume, as with most presence tools, there will be some level of granularity about how you allow others to see exactly where you are. A stealth mode, putting you at work or Antarctica might be useful for skipping out.
Skyhook is neat. But it's yet another Geo service that is effectively USA only. Gaar!